Skip to main content

​
Install

npm install @withboundary/contract @withboundary/sdk

​
Set the API key

Get an API key from the Boundary dashboard. The SDK reads BOUNDARY_API_KEY from the environment by default. 
export BOUNDARY_API_KEY=bnd_live_...

​
Wire a logger to your contract

import { z } from "zod";
import { defineContract } from "@withboundary/contract";
import { createBoundaryLogger } from "@withboundary/sdk";

const logger = createBoundaryLogger({
  environment: "production",  // "production" | "staging" | "development"
});

const contract = defineContract({
  name: "lead-scoring",       // appears on every event
  schema: z.object({
    tier: z.enum(["hot", "warm", "cold"]),
    score: z.number().min(0).max(100),
  }),
  rules: [
    (d) => d.tier !== "hot" || d.score > 70
      || `hot leads require score > 70, got ${d.score}`,
  ],
  logger,
});

​
Run a contract

const result = await contract.accept(async (attempt) => {
  const res = await openai.responses.create({
    model: "gpt-4.1",
    input: ["Score this lead", ...attempt.repairs],
  });
  return res.output_text;
});
Every accept() produces one event at the end of the run. The event is queued, batched, and shipped to Boundary’s ingest endpoint.

​
What gets sent

The SDK’s default capture policy is conservative. On a successful run you’ll see roughly: 
{
  "contractName": "lead-scoring",
  "environment": "production",
  "timestamp": "2026-04-20T09:45:12.104Z",
  "attempt": 2,
  "maxAttempts": 3,
  "ok": true,
  "durationMs": 1843,
  "repairs": [
    { "role": "user", "content": "hot leads require score > 70, got 25" }
  ],
  "rulesCount": 1,
  "sdk": { "name": "@withboundary/sdk", "version": "0.3.1", "runtime": "node/22.12.0" }
}
Raw LLM input and output are not included unless you opt in — see Capture policy.

​
Dev-safe by default

If BOUNDARY_API_KEY is not set and you don’t pass a custom write, createBoundaryLogger returns null. Passing null to defineContract is a no-op — the contract runs normally, no events sent, no errors. 
// Works in prod. No-op locally.
const logger = createBoundaryLogger();

​
Next steps

Capture policy

Turn raw inputs/outputs on or off

Redaction

Scrub PII before events leave the process

Shutdown

Drain the queue on serverless / edge / workers

createBoundaryLogger

Every option, with defaults